The present invention relates to a method for producing single microlenses or an array of microlenses composed of a glass-type material. According to the method, a first substrate having a surface containing impressions is provided, a second substrate composed of the glass-type material is placed over the first substrate at least partially overlapping it and is joined with the same under vacuum conditions, moreover the substrate composite is tempered in such a manner that the second substrate softens and flows into the impressions in the first substrate thereby structuring the side of the second substrate facing away from the first substrate to form at least one microlens surface.
Furthermore, an alternative method for producing single microlenses or an array of microlenses made of a glass-type material is described in which a first substrate having a surface containing impressions, a second substrate composed of the glass-type material is placed over the first substrate at least partially overlapping it and is joined with the same, with a gaseous medium being enclosed in the impressions between the first substrate and the second substrate and the substrate composite being tempered in such a manner that the second substrate softens and the expanding gaseous medium is displaced in the region of the impressions, thereby structuring the side of the second substrate facing away from the first substrate to form at least one convex microlens surface.
WO 01/38240 A1 describes a method for producing micromechanical and, in particular, microoptical components composed of glass-type materials using technologies to structure semiconductor substrates in order to produce functional elements made of glass in the micrometer and submicrometer range by means of glass-flow processes. In a first step, the impressions, which may be obtained by means of prior art standard lithography and etching methods, are placed in a preferably plane semiconductor surface. The prestructured semiconductor substrate is then joined with a plane substrate composed of a glass-type material, for example by means of anodic bonding, and then heated above the softening temperature of the glass-type material. If a vacuum or low pressure prevails in the cavity enclosed by the respective impression in the semiconductor material and the plane glass-type substrate, parts of the softened glass-type material are able to flow into the cavity. However, if a gaseous medium, for example air, is enclosed in the cavity in which, for example, the plane glass-type substrate is joined with the structured semiconductor substrate under normal pressure conditions, the gaseous medium located in the cavity expands due to tempering and displaces the softened glass-type material located directly over the cavity.
In the first case, a concave shaped microlens structure forms inside the surface of the glass substrate facing the semiconductor substrate. On the other hand, in the second case the local displacement leads to a convex shaped microlens structure. In both cases the resulting curvature of the microlens surface is dependent on the type and duration of tempering but, in particular, on the shape and size of the respective individual impressions inside the semiconductor substrate. With the aid of the prior art method described in the preceding, spherically or elliptically symmetrical microlens surface can be produced.
U.S. Pat. No. 4,883,524 also describes with reference to FIG. 6 shown therein a glass-flow method which determines the shape of a binocular lens, in which local flowing off of the melted glass into a concave impression in the form of an ophthalmic lens of the optical near part of a two-focal lens glass is producible.